.imgicon-shutdown{
    background:url(../img/icons/shutdown.png) no-repeat center center;
}
.imgicon-text-editor{
    background:url(../img/icons/text_editor.png) no-repeat center center;
}
.imgicon-ubuntu{
    background:url(../img/icons/ubuntu.png) no-repeat center center;
}
.imgicon-tools{
    background:url(../img/icons/tools.png) no-repeat center center;
}